Benzoxazole ultraviolet stabilizers and their use in organic compositions

ABSTRACT

The invention relates to certain benzoxazole bichromophoric compounds which have been found to be effective ultraviolet stabilizers. The invention also relates to ultraviolet degradable organic compositions containing a stabilizing amount of a certain benzoxazole bichromophoric compound to prevent such degradation. These stabilizers are effective in the presence of other additives commonly employed in polymeric compositions including, for example, pigments, colorants, fillers, reinforcing agents and the like. These ultraviolet stabilizers may also be incorporated into the organic compositions such as polymers by adding to the polymer melt or dissolved in the polymer dope, coated on the exterior of the shaped or molded article, film or extruded fiber.

This invention relates to ultraviolet stabilizers, more particularly,the invention relates to stabilization of organic compositions againstdeterioration resulting from the exposure to light with a new class ofdiesters of resorcinol compounds.

The degradative effects of ultraviolet light on various organiccompositions is well known in the art. The photodeterioration ordegradation is of particular concern with organic photo-degradablecompositions which are exposed to ultraviolet light, such as sunlight,for long periods of time. One group of such photodegradable organiccompositions is polymeric compositions such as polyolefins, polyestersand the like. On exposure to sunlight for extended periods of time,these polymeric compositions degrade and their physical properties arereduced to render the polymeric composition less useful for mostapplications. Therefore, considerable effort has been directed toproviding a solution to the photodegradation problem of polymericcompositions. As a result of this effort, there have been discoveredmany additives and stabilizers which improve the stability of polymericcompositions.

Moreover, various organic compounds exhibit the power to absorbelectromagnetic radiations within the band of 2900 to 4000 A. and whenincorporated in various plastic materials such as transparent sheets,the resultant sheet acts as a filter for all of the radiation passingthrough and will transmit only such radiations as are not absorbed bythe sheet and/or the absorbing agent. It is thus possible to screen outundesirable radiations and minimize the resulting transparent sheet as afilter in many technical and commercial applications such as wrappingsfor food products and the like.

While there are many additives, stabilizers and mixtures thereof whichare known in the art to improve the ultraviolet light stability oforganic compositions, there is a need in the art for more efficient andeffective stabilizers to prevent the photo-degradation of organiccompositions susceptible to photodegradation. Therefore, to provide amore effective and efficient ultraviolet stabilizer for organiccompositions susceptible to such degradation would be an advance in thestate of the art.

It is, therefore, an object of the present invention to provide moreeffective and efficient ultraviolet light stabilizer compositions.

Another object of the present invention is to provide usefulcompositions characterized by improved resistance to ultravioletdegradation and deterioration.

It is still another object of the present invention to providecompositions containing diesters of aromatic diols which are resistantto ultraviolet degradation.

A further object of this invention to provide processes for improvingthe resistance of organic materials to deterioration and degradation byactinic radiation and especially ultraviolet radiation.

A still further object of this invention to provide compositions andprocesses for improving the resistance of organic materials todeterioration and degradation by actinic radiations including short wavelength visible radiations.

Other objects will appear as the description proceeds.

In accordance with the present invention aryl diesters of aromaticcompounds are provided which can be used as ultraviolet stabilizers.These compositions, according to the present invention, have thefollowing structure ##STR1## wherein A is a benzoid or heterocyclicgroup having the following structure: ##STR2## wherein X and Y are acarbon atom or a nitrogen atom;

Z is an oxygen atom, a sulfur atom, a nitrogen atom, a nitrogen atomcontaining a hydrogen atom or a substituted or unsubstituted lower alkylgroup containing 1 to 12 carbon atoms;

R₁ and R₂ are either substituted and unsubstituted alkyl groupscontaining 1 to 20 carbon atoms or substituted and unsubstituted arylgroups containing 6, 12 or 18 carbon atoms; R₃, R₄, R₅, R₆ and R₇ arehydrogen, lower alkyl, substituted lower alkyl, cycloalkyl, substitutedcycloalkyl, aryl, halogen, substituted aryl, lower alkylaryl,aryl-substituted-aryl, alkoxy, carboxy, nitrile, and the substituents R₃and R₄, R₄ and R₅, R₅ and R₆, R₆ and R₇, combined with the carbon atomsto which they are attached, are joined alkylene groups completing acarboxylic ring which can be substituted with any of the substituentslisted above for R₃, R₄, R₅, R₆ and R₇.

I is a substituent listed above for R₃, R₄, R₅ and R₆ and is present onall positions of the benzenoid ring, except the carbon atom attached tothe Y substituent and the carbon atom attached to the carboxyl groupconnecting the heterocyclic aromatic A group with the aromatic B group.The carbonyl connecting group is attached to the benzoin ring in eitherthe meta or para position from the carbon atom connected to the Ysubstituent. The I substituents can all be one of the substituentslisted above or different listed substituents.

The group C is a moiety consisting of vinyl, lower alkyloxy,oxy-lower-alkyl and oxy;

The group D is a moiety having the structure ##STR3## wherein X and Yare a carbon atom or a nitrogen atom;

Z is an oxygen atom, a sulfur atom, a nitrogen atom, or a nitrogen atomcontaining a hydrogen atom or substituted or unsubstituted lower alkylgroup having 1 to 12 carbon atoms;

R₃, r₄, r₅, r₆ and R₇ are hydrogen, lower alkyl, substituted loweralkyl, cycloalkyl, substituted cycloalkyl, aryl, substituted aryl, loweralkylaryl, aryl-substituted-aryl, chloro, bromo, alkoxy, substitutedamino, cyano, carboxy and the substituents R₃ and R₄, R₄ and R₅, and R₅and R₆, combined with the carbon atoms to which they are attached, arejoined alkylene groups completing a carbocyclic ring, which ring canalso be substituted with one or more of the substituents listed abovefor R₃, R₄, R₅ and R₆.

I is a substituent listed above for R₃, R₄, R₅ and R₆ and is present onall positions of the benzenoid ring, except the carbon atom attached tothe Y substituent and the carbon atom attached to the carboxyl groupconnecting the heterocyclic aromatic A group with the aromatic B group.The carbonyl connecting group is attached to the benzoin ring in eitherthe meta or para position from the carbon atom connected to the Ysubstituent. The I substituents can all be one of the substituentslisted above or different listed substituents.

As hereinbefore used, the term "lower alkyl" denotes branched orunbranched, substituted or unsubstituted alkyl groups containing 1 to 12carbon atoms. The "alk" of the alkoxy or carboalkoxy denotes an alkylgroup of 1 to 20 carbon atoms. The substituted alkyl, aryl, orcycloalkyl group can be substituted with any of the substituents listedhereinbefore for R₃.

B is an aryl group having the formula ##STR4## wherein the carboxysattached ortho, meta, or para, at least one of R₈, R₉, R₁₀, R₁₁ ishydrogen in the ortho position to the carboxy linking group and theother substituents R₈ -R₁₁ are hydrogen, lower alkyl, substituted loweralkyl, cycloalkyl, lower alkylaryl, aryl-substituted-aryl, alkoxy,carboxy, nitrile, chloro, bromo, and the substituents R₈ -R₁₁, combinedwith the carbon atoms to which they are attached, are joined alkylidenegroups completing a carbocyclic ring which can be substituted with anyof the substituents listed above for R₈ -R₁₁.

A' is an aryl group such as phenyl, substituted phenyl, naphyl orsubstituted naphyl or the same benzoid or heterocyclic group as A.Substituents on the A' substituted phenyl and naphyl groups can be thesame as I described hereinabove.

Suitable A groups having the structure ##STR5## are, for example,dialkylanilines such as dimethylaniline, diethylaniline,bis-(β-chloroethyl)aniline, bis-(β-hydroxyethyl)aniline,di-n-propylaniline, and the like; arylalkylanilines such asmethylphenylaniline, ethylphenylaniline, and the like; and diarylanilines such as diphenylaniline di-(p-alkoxyphenyl)aniline,di-(p-halophenyl)aniline, di-(p-cyanophenyl)aniline, and the like.

Suitable A groups having the structure ##STR6## are, for example,substituted and unsubstituted benzoxazoles, benzotriazoles,benzothiazoles, and benzamidazoles.

Examples of such suitable benzoxazole moieties are those having theformula ##STR7## such as 4-(5,6-dimethyl-2-benzoxazolyl)phenyl,4-(2-benzoxazolyl)-2-chlorophenyl, and3-(5-chloro-2-benzoxazolyl)phenyl.

Examples of suitable benzotriazole moieties are those having the formula##STR8## such as 4-(5-chloro-2H-benzotriazol-2-yl)phenyl,4-(2H-benzotriazol-2-yl)phenyl, and4-(5-methoxy-2H-benzotriazol-2-yl)phenyl.

Examples of suitable benzothiazole moieties are those having the formula##STR9## such as 4-(5,6-dimethyl-2-benzothiazolyl)phenyl,4-(2-benzothiazolyl)-2-chlorophenyl, and3-(5-chloro-2-benzothiazolyl)phenyl.

Examples of suitable benzimidazole moieties are those having the formula##STR10## wherein Q is hydrogen or a substituted or unsubstituted loweralkyl group containing 1 to 12 carbon atoms, such as4-(5,6-dimethyl-2-benzimidazolyl)-phenyl,4-(2-benzimidazolyl)-2-chlorophenyl,3-(5-chloro-2-benzimidazolyl)-phenyl,4-(1-methyl-2-benzimidazolyl)phenyl,4-(1-ethyl-5-chloro-2-benzimidazolyl)phenyl, and N-ethyl4-(2-benzimidazolyl)phenyl.

Examples of suitable indole moieties are those having the formula##STR11## wherein G is the same as R₃ and Q is hydrogen or a substitutedor unsubstituted lower alkyl containing 1 to 12 carbon atoms, such as3-(1-ethyl-3-cyano-2-indolyl)phenyl, 3-(5-chloro-2-indolyl)phenyl,3-(1-methyl-2-indolyl)phenyl, 3-(3-methyl-2-indolyl)phenyl,3-(3-chloro-2-indolyl)phenyl, 3-(5-acetamido-2-indolyl)phenyl,3-(2-indolyl)phenyl, 4-(1-ethyl-2-indolyl)phenyl,4-(3-cyano-2-indolyl)phenyl, 4-(5-methoxy-2-indolyl)phenyl,4-(1-methyl-2-indolyl)phenyl, 4-(3-methyl-5-phenyl-2-indolyl)phenyl,4-(3,5-dichloro-2-indolyl)phenyl, 4-(2-indolyl)phenyl,4-chloro-2-indolylphenyl, and 4-methoxy-2-indolylphenyl.

Suitable A groups having the structure ##STR12## are oxadiazole,benzopyrole, triazine, thiadiazole, substituted and unsubstituted2-oxadiazolyl, 2-thiazolyl, 2-triazolyl, 2-oxazolyl, and 2-imidazolyland the like.

Examples of suitable oxadizaole moieties are those having the formula

such as 5-phenyl-1,3,4-oxadiazol-2-yl,5-methylsulfonyl-1,3,4-oxadiazol-2-yl,5-(2,4-dichlorophenyl)-1,3,4-oxadiazol-2-yl,5-(4-chlorophenyl)-1,3,4-oxadizaol-2-yl, 5-methyl-1,3,4-oxadiazol-2-yl,5-(4-phenyl)phenyl-1,3,4-oxadiazol-2-yl, 5-cyano-1,3,4-oxadiazol-2-yl,5-(4-cyanophenyl)-1,3,4-oxadiazol-2-yl, and5-(4-methoxyphenyl)-1,3,4-oxadiazol-2-yl, and the like.

Examples of suitable 2-thiadiazolyl moieties are those having theformula: ##STR14## such as 5-phenyl-1,3,4-thiadiazol-2-yl,5-(4-chlorophenyl)-1,3,4-thiadiazol-2-yl,5-methylsulfonyl-1,3,4-thiadiazol-2-yl, 5-ethoxy-1,3,4-thiadiazol-2-yl,5-phenyl-1,3,4-thiadiazol-2-yl,5-(4-phenyl)phenyl-1,3,4-thiadiazol-2-yl,5-cyclohexyl-1,3,4-thiadiazol-2-yl,5-(3-methoxyphenyl)-1,3,4-thiadiazol-2-yl, and5-cyano-1,3,4-thiadiazol-2-yl, and the like.

Examples of suitable 2-triazolyl moieties are those having the formula:##STR15## wherein W is hydrogen or a substituted or unsubstituted loweralkyl group containing 1 to 12 carbon atoms, such as5-phenyl-1,3,4-triazol-2-yl, 5-(4-cyanophenyl)-1,3,4-triazol-2-yl,5-cyano-1,3,4-triazol-2-yl, 4-(4-methoxyphenyl)-1,3,4-triazol-2-yl,1-(n-butyl)-5-(2,4-dichlorophenyl)-1,3,4-triazol-2-yl,1,3,4-triazol-2-yl, 5-phenyl-1,3,4-triazol-2-yl,5-methylsulfonyl-1,3,4-triazol-2-yl,1-methyl-5-phenyl-1,3,4-triazol-2-yl, and the like.

Examples of suitable 2-oxazolyl moieties are those having the formula:##STR16## wherein J is the same as R₁, such as 5-phenyl-2-oxazolyl,4,5-diphenyl-2-oxazolyl, 4,5-dimethyl-2-oxazolyl,4-chloro-5-cyano-2-oxazolyl, 4-phenyl-5-cyano-2-oxazolyl,5-methylsulfonyl-2-oxazolyl, 5-cyclohexyl-2-oxazolyl,4,5-dichloro-2-oxazolyl, 5-ethoxy-2-oxazolyl, and the like.

Examples of suitable 2-thiazolyls are thiazolyls having the formula:##STR17## wherein J is the same as R₁, such as4-phenyl-5-chloro-2-thiazolyl, 4,5-dichloro-2-thiazolyl,4-chloro-5-cyano-2-thiazolyl, 4-ethoxy-5-phenyl-2-thiazolyl,4,5-dimethyl-2-thiazolyl, 4,5-dicyano-2-thiazolyl, 5-phenyl-2-thiazolyl,and the like.

Examples of suitable 2-imidazolyl moieties are those having the formula:##STR18## wherein J is the same as R₁ and W is hydrogen or a substitutedor unsubstituted lower alkyl having 1 to 12 carbon atoms, such as1-methyl-4,5-diphenyl-2-imidazolyl, 4-chloro-5-cyano-2-imidazolyl,5-phenyl-2-imidazolyl, 1-ethyl-5-phenyl-2-imidazolyl,4,5-diphenyl-2-imidazolyl, 1-benzyl-4-phenyl-5-cyano-2-imidazolyl,1-methyl-4-cyano-2-imidazolyl,4-methoxy-5-phenyl-2-imidazolyl-4,5-dichloro-1-benzyl-2-imidazolyl, andthe like.

Suitable A groups having the formula ##STR19## are, for example,substituted and unsubstituted 2-benzoxazolyl, 2-benzothiazolyl,2-benzimidazolyl, benzotriazolyl and 2-imidolyl.

Examples of suitable 2-benzoxazolyl moieties are those having theformula ##STR20## such as 5,6-dimethyl-2-benzoxazolyl, 2-benzoxazolyl,5-chloro-2-benzoxazolyl, 5,6-dichloro-2-benzoxazolyl,4,5-diethyl-2-benzoxazolyl, 5-cyano-2-benzoxazolyl,5-methoxy-6-methyl-2-benzoxazolyl, 4-chloro-5-phenyl-2-oxazolyl.

Examples of suitable 2-benzothiazolyl moieties are those having theformula ##STR21## such as 2-benzothiazolyl,5,6-dimethyl-2-benzothiazolyl, 5,6-dichloro-2-benzothiazolyl,5-chloro-2-benzothiazolyl, 5-methoxy-2-benzothiazolyl,6-methylsulfonyl-2-benzothiazolyl, 6-cyano-2-benzothiazolyl,6-methylthio-2-benzothiazolyl, and 6-methyl-2-benzothiazolyl.

Examples of suitable 2-benzimidazolyl moieties are those having theformula ##STR22## wherein Q is hydrogen or a substituted orunsubstituted lower alkyl containing 1 to 12 carbon atoms, such as2-benzimidazolyl, 1-methyl-2-benzimidazolyl,1,5,6-trimethyl-2-benzimidazolyl, 6-cyano-1-ethyl-2-benzimidazolyl,6-chloro-2-benzimidazolyl, 5-methoxy-1-benzyl-2-benzimidazolyl,6-methylsulfonyl-2-benzimidazolyl, 4-methoxy-1-methyl-2-benzimidazolyl,and the like.

Examples of suitable indole moieties are those having the formula##STR23## wherein G is the same as R₃ and Q is hydrogen or a substitutedor unsubstituted lower alkyl containing 1 to 12 carbon atoms. Suchsuitable indole moieties are, for example, 1-ethyl-3-cyano-2-indolyl,5-chloro-2-indolyl, 1-methyl-2-indolyl, 3-methyl-2-indolyl,3-chloro-2-indolyl, 5-acetamido-2-indolyl, 1-benzyl-2-indolyl,1-ethyl-2-indolyl, 3-cyano-2-indolyl, 5-methoxy-2-indolyl,1-methyl-2-indolyl, 3-methyl-5-phenyl-2-indolyl, 3,5-dichloro-2-indolyland 2-indolyl.

Examples of suitable triazine moieties are those having the formula##STR24## where Q is hydrogen or lower alkyl containing 1 to 12 carbonatoms, such as 1H-5-phenyl-1,3,4-triazol-2-yl,1H-5-methylsulfonyl-1,3,4-triazol-2-yl,1-methyl-5-phenyl-1,3,4-triazol-2-yl, and1-ethyl-5-(4-chlorophenyl)-1,3,4-2-yl.

Examples of suitable thiadiazole moieties are those having the formula##STR25## such as 5-phenyl-1,3,4-thiadiazol-2-yl,5-(4-chlorophenyl)-1,3,4-thiadiazol-2-yl and5-methylsulfonyl-1,3,4-thiadiazol-2-yl.

Suitable A' groups can be the same as A or phenyl or substitutedphenyls, naphyl or substituted naphyl and the like.

Suitable B groups are phenyl moieties having the formula ##STR26## arefor example, catechol, resorcinol, p-hydroquinone, 4-methylcatechol,4-methoxycatechol, 5-methylresorcinol, 5-methoxyresorcinol,2,5-dimethylresorcinol, tolylhydroquinone, 2,5-dimethylhydroquinone,t-butylhydroquinone and 5-t-butylresorcinol.

The bichromophoric compounds can be prepared by reacting acid chlorideswith dihydroxybenzenes.

For example, one group of bichromics ultraviolet stabilizer according tothe present invention is prepared as follows: ##STR27## wherein R₃through R₁₁ and I and II are defined hereinabove.

It is necessary that at least one of R₈, R₉ or R₁₁ be hydrogen so that,on exposure to ultraviolet light, the aryl ester of the heterocyclicaromatic acid is capable by a "photo-Fries" rearrangement of forming aphenol group in that position formerly joined through an oxygen atom tothe carbonyl linking group, as for example ##STR28##

The acid chlorides (I) were prepared by reaction of the correspondingacids [see Zh. Obshch. Khim., 38, 1001-5 (1968); Chem. Abstr., 69, 96568(1968)] with freshly distilled thionyl chloride [see J. Chem. Soc., 101,2476 (1912)]. The aromatic diols such as resorcinol, catechol orp-hydroquinone were obtained from commercial sources, or were preparedby standard methods; a necessary requirement is that one of thepositions adjacent the hydroxyl moiety on the benzene ring of the diolbe unsubstituted.

The heterocyclic phenylene dibenzoate compositions can be added toorganic compositions which are susceptible to ultraviolet degradation.Such compositions include, for example, polymeric compositions such aspolyester fiber and moldable compositions, such as polyethyleneterephthalate, polytetramethylene terephthalate and the like;polyolefins such as, for example, high, medium and low densitypolyethylene, polypropylene, polybutene and the like; polyamides such asN-methoxymethyl polyhexamethylene adipamide and the like;polycarbonates; polyvinyl chloride and copolymers; cellulose esters;acrylic/butadiene/styrene plastic; polyacrylics such as methylmethacrylate; polystyrene; gelatin; vinylidene chloride copolymers suchas vinylidene chloride/vinyl acetate copolymers; ethylene/vinyl acetatecopolymers; cellulose esters such as methyl cellulose; polyvinyl esterssuch as polyvinyl acetate; polyethylene oxides; polyvinyl acetals;polyformaldehydes; and polyurethanes. Such compositions also includenatural and synthetic rubbers, such as polybutadiene, and unsaturatedorganic compositions such as oils and the like, as well as compositionscontaining such organic compositions.

The heterocyclic phenylene dibenzoate compositions as effectiveultraviolet stabilizers or screening agents are generally used in anamount of from 0.01 to 10%, by weight, based on the weight of theorganic material to which they are added. While a detectable amount ofultraviolet screening and stabilization may be obtained with amountsless than 0.01%, this amount of stabilization or screening would be oflittle practical utility in a commercial application. Moreover, whileamounts greater than 10%, by weight, provide effective ultravioletstability and screening, such concentrations are undesirable because ofcost and the deleterious effect which such concentrations may have onthe mechanical properties of the organic composition in which thestabilizer is incorporated. Preferably, the stabilizer is used in anamount of from about 0.1 to about 3%, by weight. For example, an amountof 2% by weight of the stabilizer effectively stabilizes celluloseacetate butyrate plastic compositions.

The ultraviolet stabilized organic compositions containing thestabilizers of the present invention may also contain other additives,pigments, colorants, stabilizers and the like. For example, polymericcompositions, such as polyolefins, may also contain and generally docontain other additives such as white or colored pigments or colorants,antioxidants, plasticizers, flow aids, processing aids, polymericmodifiers and the like.

These novel heterocyclic phenylene dibenzoate ultraviolet stabilizersmay be incorporated into organic compositions by melt-blending or may beadded onto the surface of an organic plastic material prior to beingmolded into a suitable object, or added to the surface of the moldedobject. These materials can also be added to coatings and the like whichcan be applied to the surface of a molded object.

This invention will be further illustrated by the following examplesalthough it will be understood that these examples are included merelyfor purposes of illustration and are not intended to limit the scope ofthe invention.

EXAMPLE 1

m-Phenylene 4-(2-benzoxazolyl)dibenzoate can be prepared by thefollowing procedure: ##STR29##

A solution containing 14.4 g (0.05 mole) of 4-(2-benzoxazolyl)benzoylchloride, 10.7 g. (0.05 mole) of resorcinol monobenzoate, and 5 ml. ofpyridine in 250 ml. of toluene is refluxed for 15 hours. The solution isfiltered hot and, upon concentration of the filtrate, 17.09 g. (78%) ofm-phenylene 4-(2-benzoxazolyl)dibenzoate (1) is filtered as acrystalline solid having a melting point of 174°-175° C.: UV (CH₃ CN)λmax. 318 nm. (ε35,600).

Other phenylene benzoxazolyldibenzoates can be prepared by substitutingother benzoxazolylbenzoyl chlorides, such as4(5,6-dimethyl-2-benzoxazolyl)benzoyl chloride,4-(2-benzoxazolyl)-2-chlorobenzoyl chloride,3-(5-chloro-2-benzoxazolyl)benzoyl chloride,4-(5,6-dichloro-2-benzoxazolyl)benzoyl chloride,(4-(5,6-diethyl-2-benzoxazolyl)benzoyl chloride,4-(5-cyano-2-benzoxazolyl)benzoyl chloride,4-(5-methoxy-6-methyl-2-benzoxazolyl)benzoyl chloride, for4-(2-benzoxazolyl)benzoyl chloride.

EXAMPLE 2

m-Phenylene bis(p-2-benzoxazolylbenzoate) can be prepared by thefollowing procedure: ##STR30##

A solution containing 2.75 g. (0.025 mole) of resorcinol and 2.0 g.(0.050 mole) of sodium hydroxide in 75 ml. of water is added dropwise toa chloroform solution (200 ml.) of 4-(2-benzoxazolyl)benzoyl chloride(12.85 g., 0.050 mole). The resulting solution is refluxed for 4 hours.An off-white solid which appears between the layers is filtered andair-dried and amounts to 10.60 g. (77%) of m-phenylenebis(p-2-benzoxazolylbenzoate) (2) having a melting point of 273°-274°C.: UV (CH₃ CN) λmax. 319 nm. (ε73,000).

Other phenylene benzoxazolyldibenzoates can be prepared by substitutingother benzoazolylbenzoyl chlorides, such as4-(5,6-dimethyl-2-benzoxazolyl)benzoyl chloride,4-(2-benzoxazolyl)-2-chlorobenzoyl chloride,3-(5-chloro-2-benzoxazolyl)benzoyl chloride,4-(5,6-dichloro-2-benzoxazolyl)benzoyl chloride4-(5,6-diethyl-2-benzoxazolyl)benzoyl chloride,4-(5-cyano-2-benzoxazolyl)benzoyl chloride,4-(5-methoxy-6-methyl-2-benzoxazolyl)benzoyl chloride, for4-(2-benzoxazolyl)benzoyl chloride.

Also, other phenylene benzoxazolyldibenzoates can be prepared bysubstituting other aromatic diols, such as 5-methylresorcinol,5-methoxyresorcinol, 5-chlororesorcinol, 2-methyl-p-hydroquinone,2-methoxy-p-hydroquinone, 2,5-dimethyl-p-hydroquinone,2,5-dimethoxy-p-hydroquinone, 4-methylcatechol, 4-methoxycatechol,4-chlorocatechol, 4,5-dimethylcatechol, 4,5-dimethoxycatechol,4,5-dichlorocatechol, for resorcinol.

EXAMPLE 3

o-Phenylene bis(p-2-benzoxazolylbenzoate) can be prepared by thefollowing procedure: ##STR31##

A solution containing 1.65 g. (0.015 mole) of catechol and 1.20 g. (0.03mole) of sodium hydroxide in 20 ml. of water was added to a chloroformsolution (60 ml.) of 4-[2-benzoxazolyl]benzoyl chloride (7.70 g., 0.03mole) and refluxed for 5 hours. An off-white solid which appears betweenthe layers was filtered, washed with ether and air dried and amounts to7.01 g. (84%) of o-phenylene bis(p-2-benzoxazolyl)benzoate (5) (mp221°-225°) UV (CH₂ Cl₂) max 308 nm. (ε50,000).

EXAMPLE 4

m-Phenylene 4-[2-(5,6-dimethyl-2-benzoxazolyl)vinyl]dibenzoate can beprepared by the following procedure: ##STR32##

A solution containing 3.12 g. (0.01 mole) of4-[2-(5,6-dimethyl-2-benzoxazolyl)vinyl]benzoyl chloride, 2.15 g. (0.01mole) of resorcinol monobenzoate, and 10 ml. of pyridine in 150 ml. oftoluene is refluxed for 5 hours. The solution is filtered hot and, uponconcentration of the filtrate, 3.53 g. (72%) of m-phenylene4-[2-(5,6-dimethyl-2-benzoxazolyl)vinyl]dibenzoate (3) is obtained as alight yellow solid having a melting point of 198°-199° C.: UV (CH₃ CN)εmax. 358 nm. (ε40,500); ε325 = 26,000.

EXAMPLE 5

m-Phenylene 4,4'-bis[2-(5,6-dimethyl-2-benzoxazolyl)vinyl]dibenzoate canbe prepared by the following procedure: ##STR33##

A solution containing 1.10 g. (0.01 mole) of resorcinol and 0.83 g.(0.02 mole) of sodium hydroxide in 50 ml. of water is added dropwise toa chloroform solution (125 ml.) of4-[2-(5,6-dimethyl-2-benzoxazolyl)vinyl]benzoyl chloride (6.23 g., 0.02mole) and refluxed for 18 hours. The organic layer is separated, washedwith water, dried, and concentrated to give 4.56 g. (40%) of m-phenylene4,4'-bis-[2-(5,6-dimethyl-2-benzoxazolyl)vinyl]dibenzoate (4) having amelting point of 225°-227° C.: UV (CH₃ CN) εmax. 357 nm. (70,000) ε325 =44,000.

EXAMPLE 6

The ultraviolet stabilization provided by the heterocyclic phenylbenzoates of the present invention is shown in poly(tetramethyleneterephthalate) in the following table.

Flat bars of polyester containing these stabilizers are prepared andexposed to a 280 -700 nm. mercury lamp source until a flatwise impactstrength of less than 6 is obtained (initial values are all greater than15). The results are summarized in Table 1. Stabilizers 1 to 4 are:

1. m-phenylene 4-(2-benzoxazolyl)dibenzoate

2. m-phenylene bis(p-2-benzoxazolylbenzoate)

3. m-phenylene 4-[2-(5,6-dimethyl-2-benzoxazolyl)vinyl]dibenzoate

4. m-phenylene 4,4'-bis[2-(5,6-dimethyl-2-benzoxazolyl)vinyl]dibenzoate.

                  Table 1                                                         ______________________________________                                        Effect of Stabilizers on Time-To-Loss of Impact                               Strength of Polytetramethylene Terephthalate                                  ______________________________________                                                            Time-To-Loss of                                           Stabilizer (concentration)                                                                        Impact Strength (hr.)                                     ______________________________________                                        None                <500 (300)                                                Tinuvin P (0.5)     <1000                                                     1 (0.5)               1000                                                    2 (0.5)             >1700                                                     3 (0.5)             >1000                                                     4 (0.5)             >1000                                                     ______________________________________                                    

These diesters of aromatic acid compositions find particular utility asultraviolet stabilizers in organic compositions requiring ultravioletstability. Such compositions include polymeric compositions such as, forexample, polyester fiber and molding compositions; poly-α-olefins;polyamides; acrylics; cellulose esters and the like; as well as moldedor shaped articles, film and coatings formed from such materials, andthe like. Such compositions also include natural and synthetic rubbers,such as natural rubber, as well as organic materials such as oils, fats,and unsaturated organic materials, and materials having such materialscontained therein such as paints, varnishes, cosmetics and the like.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

We claim:
 1. A composition of matter having the formula:##STR34##wherein R₄ is hydrogen, lower alkyl, or nitrile; R₅ is hydrogenor lower alkyl; and at least one R₈, R₉, R₁₀ and R₁₁ is hydrogen, andthe remainder are hydrogen, lower alkyl, alkoxy containing 1 to 20carbon atoms, halogen, or nitrile or carboalkoxy containing 1 to 20carbon atoms.
 2. A composition of matter having the formula:##STR35##wherein R₄ is hydrogen, lower alkyl, or nitrile; R₅ is hydrogenor lower alkyl; and at least one R₈, R₉, and R₁₁ is hydrogen, and theremaining R₈, R₉, R₁₀ and R₁₁ are hydrogen, lower alkyl, alkoxycontaining 1 to 20 carbon atoms, halogen or nitrile.
 3. A composition ofmatter having the formula: ##STR36##wherein R₄ is hydrogen, phenyl loweralkyl wherein said alkyl contains not more than three carbon atoms orlower alkyl; R₅ is hydrogen or lower alkyl; and at least one R₈, R₉, andR₁₁ are hydrogen, and the remaining R₈, R₉, R₁₀ and R₁₁ are hydrogen,lower alkyl, alkoxy containing 1 to 20 carbon atoms, halogen, nitrile,or carboxy.
 4. A composition of matter having the formula: ##STR37##wherein R₄ is hydrogen, lower alkyl, or nitrile; R₅ is hydrogen or loweralkyl; and at least R₈, R₉, and R₁₁ is hydrogen and the remaining R₈,R₉, R₁₀ and R₁₁ are hydrogen, lower alkyl, alkoxy containing 1 to 20carbon atoms, halogen or nitrile or carboxy.
 5. A composition of matterhaving the formula: ##STR38##wherein R₄ is hydrogen or lower alkyl andR₅ is hydrogen or lower alkyl.
 6. A composition of matter according toclaim 5 having the formula: ##STR39##
 9. A composition of matter havingthe formula: ##STR40##
 15. A composition of matter having the formula: